Weathering dynamics of Large Igneous Provinces (LIPs): A case study from the Lesotho Highlands
Weathering dynamics of Large Igneous Provinces (LIPs): A case study from the Lesotho Highlands
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大火成岩省 (LIP) 的风化动态：莱索托高地的案例研究
DOI：
10.1016/j.epsl.2019.115871
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发表时间：
2020-01
影响因子：
5.3
通讯作者：
Gaojun Li
中科院分区：
文献类型：
--
作者：
Yang Chen;David William Hedding;Xuming Li;Abraham Carel Greyling;Gaojun Li
玄武岩地体是全球硅酸盐风化通量的重要组成部分，尽管它们的面积覆盖范围有限。火山不活跃的玄武岩区的化学风化通量与温度等气候因素之间的强烈相关性表明，玄武岩的风化可能在维持地球宜居和地质碳循环平衡方面发挥了重要作用。然而，在构造静止的克拉通上，洪水玄武岩省的侵蚀率很低，在那里观察到了风化速率对气候的明显依赖，这表明风化作用是一种“供应有限”的风化制度，因此风化通量预计将受到物理侵蚀而不是气候的控制。这项工作通过调查莱索托高地Karoo唇部的风化通量来测试洪水玄武岩的风化动力学，通过陆地宇宙成因核素测年和沉积物通量记录到那里的剥蚀率极低。莱索托高地河流的河流化学具有典型的玄武岩风化特征，阳离子以钙、镁为主，阴离子以HCO3-−为主。观察到溶质浓度的强烈的空间和季节变化，可能与稀释效应有关。然而，莱索托高地水利工程(LHWP)的巨型Katse水库有效地平均了溶质浓度的空间和季节变化。卡策水库的平均溶液浓度和长期径流给出了平均大气CO2消耗速率为0.26±0.02×106mol/km2/yr(平均值±标准差)。化学风化熔剂需要原生硅酸盐的完全蚀变，因此，鉴于剥蚀率较低，建议采用“供应受限”的风化机制。然而，莱索托高地以及其他低侵蚀玄武岩高原的化学风化速率仍然符合全球温度和玄武岩风化速率之间的相关性。提出了一种受温度调节的限产剥蚀速率，以调和观测到的化学风化速率随温度的变化与“供应受限”风化制度之间的矛盾。
Basaltic terrains contribute a significant component to the global silicate weathering flux despite their limited areal coverage. A strong correlation between chemical weathering flux and climatic factors such as temperature in volcanically inactive basaltic fields implies that weathering of basalt might have played an important role in maintaining the habitability of the Earth and the balance of the geological carbon cycle. However, the low erosion rate of flood basalt provinces on tectonically quiescent cratons, where the clear climate dependence of weathering rate has been observed, implies a ‘supply-limited’weathering regime so that weathering fluxes are expected to be controlled by physical erosion rather than climate. This work tests the weathering dynamics of flood basalts by investigating the weathering flux of the Karoo LIP on the Lesotho Highlands where an extremely low rate of denudation has been recorded through terrestrial cosmogenic nuclide dating and sediment flux. Stream chemistry of the rivers from the Lesotho Highlands shows typical characteristics of basalt weathering with Ca and Mg as the dominant cations and HCO 3− as the dominant anion. Strong spatial and seasonal variability of solute concentration, possibly linked to a dilution effect, is observed. However, the giant Katse Reservoir of the Lesotho Highlands Water Project (LHWP) effectively averages the spatial and seasonal variability of the solute concentration. The average solution concentration and long-term runoff of the Katse Reservoir give an average atmospheric CO 2 consumption rate of 0.26±0.02× 10 6 mol/km 2/yr (mean±standard deviation). The chemical weathering flux requires complete alteration of primary silicates and, therefore, a ‘supply-limited’weathering regime is suggested given the low denudation rate. Nevertheless, the chemical weathering rate of the Lesotho Highlands, as well as other low-eroding basaltic plateaus, is still consistent with the global correlation between temperature and the rate of basalt weathering. A production-limited denudation rate, modulated by temperature, is suggested to reconcile the paradox between the observed temperature dependence of chemical weathering rates and ‘supply-limited’weathering regimes.
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将微量金属掺入微藻中作为古降水的新代理
影响因子：
5.3
作者：
Tao Li;Gaojun Li
通讯作者：
Gaojun Li
影响因子：
3.9
作者：
S. Riffel;P. Vasconcelos;I. Carmo;K. Farley
通讯作者：
S. Riffel;P. Vasconcelos;I. Carmo;K. Farley
DOI：
10.1111/j.1468-0459.2008.00337.x
发表时间：
2008-03
期刊：
Geografiska Annaler: Series A, Physical Geography
影响因子：
--
作者：
W. Nel;P. Sumner
通讯作者：
W. Nel;P. Sumner
影响因子：
2.7
作者：
A. Fleming;M. Summerfield;J. Stone;L. Fifield;R. Cresswell
通讯作者：
A. Fleming;M. Summerfield;J. Stone;L. Fifield;R. Cresswell
影响因子：
64.8
作者：
Ferrier, Ken L.;Huppert, Kimberly L.;Perron, J. Taylor
通讯作者：
Perron, J. Taylor